ATTRACTOR, CHAOTIC [STRANGE]Attractor characterized by the most complex form of bounded posttransient recurrent behaviour with random characteristics observed in a deterministic dissipative dynamical system.

BIFURCATIONQualitative change in the topology of the attractor-basin phase portrait (multiple points generated in Poincaré mapping), realisable under the quasistatic variation of a control parameter across its critical value.

COEFFICIENT [FACTOR], LOSSMeasure of damping capacity of a system during forced harmonic vibration, expressed by dimensionless ratio of damping energy dissipated per cycle to 2π times strain energy at the maximum displacement.

CURVE, RESONANCEPlot of a characteristic parameter of the response of an excited system in a certain vicinity of its resonance versus a chosen parameter of the system or excitation. Note: special kind of a resonance curve is e.g. an amplitude-frequency characteristic.

EXCITATION, EXTRAPARAMETRICIn a rotating system with variable moment of inertia, special kind and combination of external and parametric excitation, dependent nonlinearly upon unknown both position angle and angular velocity of the system.

POINT, EQUILIBRIUM [FIXED]1. For time-continuous dynamical systems, point in phase space towards which a solution may approach as transients decay. 2. For time-discrete dynamical systems, a finite set of points where the system visits each point in a sequential manner as a difference equation is iterated.

POINT, SADDLEUnstable equilibrium point not directly observable in a physical system, as it repels trajectories in some phase directions but attracts in others, having real eigenvalues with at least one positive and one negative eigenvalue.